<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/vue/2.5.2/vue.min.js"></script>
</head>
<body>
    <div id="app">
        <button v-on:click="hihi">click me</button>
    </div>
</body>
<script>
    var vue = new Vue({
        el:"#app",
        data: {
            items: ["1","2","3","4"],
            mess: "bitterteaer"
        },
        methods: {
            hihi: function(){
                alert(this.mess);
            }
        }
    });
</script>
</html>